Wafer purging-type shelf assembly and buffer module having the same

ABSTRACT

Disclosed herein are a wafer purging-type shelf assembly and a buffer module having the same. The wafer purging-type shelf assembly includes: a shelf formed to support a wafer receiving container; a supply nozzle configured to be connected to an injection port of the wafer receiving container; and a gas supply line configured to supply an inert gas discharged from a factory gas facility to the wafer receiving container through the supply nozzle, wherein the gas supply line includes a proportional pressure control valve unit that adjusts a supply flow rate of the inert gas to the wafer receiving container by an area control method.

RELATED APPLICATIONS

This application claims priority to Korean Patent Application No.10-2018-0115097, filed on Sep. 27, 2018, which is herein incorporated byreference in its entirety.

BACKGROUND Field

The present invention relates to a shelf assembly used in asemiconductor manufacturing process and capable of purging wafers, and abuffer module having the same.

Description of the Related Art

Generally, a semiconductor manufacturing process includes a step ofproducing a wafer, a step of processing the produced wafer throughvarious equipments, and a step of inspecting a semiconductor packageproduced through processing.

In such a processing step, the wafers may not be continuously put intovarious equipments, and are sequentially put into the next equipment asneeded after being stored for a predetermined time. Therefore,facilities for such storage are needed. The facilities for storage maybe installed on a ground of a semiconductor factory or may also beinstalled while being suspended from a ceiling.

During storage in the facilities for storage, a surface of the wafer maybe damaged by oxidation over time. In order to prevent such damage, aninert gas may be injected into a container receiving the wafer duringstorage in the facilities for storage.

A mass flow controller (MFC) is used to detect an injection amount ofthe inert gas. However, since the mass flow controller is expensive, thecost of widely installing the mass flow controller for each containerreceiving the wafer is enormous. In addition, since the mass flowcontroller has a large volume, there is a space restriction to installthe mass flow controller in a facility for integrating and storingcontainers.

Accordingly, in a case in which the mass flow controller is not used,the inert gas is continuously injected into the container in apredetermined amount. This increases the injection amount of the inertgas more than necessary, resulting in an enormous waste of the inertgas.

SUMMARY

An object of the present invention is to provide a wafer purging typeshelf assembly which precisely controls an inert gas supplied into awafer receiving container to eliminate a waste of the inert gas and mayeliminate the use of components which are expensive and require a largespace, and a buffer module having the same.

Another object of the present invention is to provide a wafer purgingtype shelf assembly which may stably supply a large amount of flow rateeven when the flow rate of an inert gas supplied into a wafer receivingcontainer needs to be sharply increased, and a buffer module having thesame.

According to an exemplary embodiment of the present invention, there isprovided a wafer purging-type shelf assembly including: a shelf formedto support a wafer receiving container; a supply nozzle configured to beconnected to an injection port of the wafer receiving container; and agas supply line configured to supply an inert gas discharged from afactory gas facility to the wafer receiving container through the supplynozzle, wherein the gas supply line includes a proportional pressurecontrol valve unit that adjusts a supply flow rate of the inert gas tothe wafer receiving container by an area control method.

The proportional pressure control valve unit may include a valve housingincluding an input port and an output port; and a piezo valve seat beinginstalled in the valve housing and adjusting a flow area of the inertgas through the input port according to an input voltage to control aflow rate of the inert gas output through the output port.

The proportional pressure control valve unit may further include arestoring spring that pressurizes the piezo valve seat in a direction ofclosing the input port.

The proportional pressure control valve unit may further include apressure sensor that measures a pressure of the inert gas output throughthe output port.

The gas supply line may further include a shelf-dedicated regulatorinstalled at an upstream side of the proportional pressure control valveunit and configured to supply the inert gas only to the proportionalpressure control valve unit at a uniform pressure.

The shelf-dedicated regulator may be disposed below the shelf.

The gas supply line may further include a flow rate sensor disposedbetween the proportional pressure control valve unit and the supplynozzle to output a flow rate of the inert gas passing through theproportional pressure control valve unit.

The gas supply line may further include a filter installed at anupstream side of the supply nozzle to filter foreign materials of theinert gas.

According to another exemplary embodiment of the present invention,there is provided a wafer purging-type shelf assembly including: a shelfon which a wafer receiving container is seated; a proportional pressurecontrol valve unit configured to adjust a supply flow rate of an inertgas supplied to the wafer receiving container from a factory gasfacility by an area control method; and a shelf-dedicated regulatorpositioned at an upstream side of the proportional pressure controlvalve unit and configured to input the inert gas only to theproportional pressure control valve unit corresponding to the shelf at auniform pressure.

The proportional pressure control valve unit may be configured to adjustthe supply flow rate of the inert gas over the time after the waferreceiving container is seated on the shelf.

The proportional pressure control valve unit may include a valve housingincluding an input port and an output port; and a piezo valve seat beinginstalled in the valve housing and adjusting a flow area of the inertgas through the input port according to an input voltage to control aflow rate of the inert gas output through the output port.

The proportional pressure control valve unit may further include apressure sensor that measures a pressure of the inert gas output throughthe output port.

The wafer purging-type shelf assembly may further include a flow ratesensor installed at a downstream side of the proportional pressurecontrol valve unit to output the flow rate of the inert gas passingthrough the proportional pressure control valve unit.

According to still another exemplary embodiment of the presentinvention, there is provided a wafer purging-type buffer moduleincluding: a storage housing including a receiving space; a shelfdisposed to support a wafer receiving container in the receiving space;and a proportional pressure control valve unit configured to adjust asupply flow rate of an inert gas supplied to the wafer receivingcontainer from a factory gas facility by an area control method.

The wafer purging-type buffer module may further include ashelf-dedicated regulator positioned at an upstream side of theproportional pressure control valve unit and configured to input theinert gas only to the proportional pressure control valve unitcorresponding to the shelf at a uniform pressure.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view showing an EFEM 100 including a buffermodule 170 according to an exemplary embodiment of the presentinvention;

FIG. 2 is an assembled perspective view showing a configuration relatedto a buffer port 220 of a buffer module 200 of FIG. 1;

FIG. 3 is an exploded perspective view of a principal part of aconfiguration related to the buffer port 220 of FIG. 2;

FIG. 4 is a block diagram describing a gas supply line 260 installed inthe buffer module 200 of FIG. 3;

FIG. 5 is a conceptual view showing a configuration of a proportionalpressure control valve unit 300 of FIG. 4;

FIG. 6 is a graph showing an experiment result on the proportionalpressure control valve unit 300 of FIG. 5;

FIG. 7 is a graph showing an ideal change of an inert gas flow ratesupplied to a FOUP C by the proportional pressure control valve unit 300of FIG. 5; and

FIG. 8 is a control block diagram for the EFEM 100 of FIG. 1.

DETAILED DESCRIPTION

Hereinafter, a wafer purging-type shelf assembly and a buffer moduleaccording to exemplary embodiments of the present invention will bedescribed in detail with reference to the accompanying drawings.Throughout the present specification, components that are the same as orsimilar to each other will be denoted by reference numerals that are thesame as or similar to each other, and a description therefor will bereplaced with a first description, even in different exemplaryembodiments.

FIG. 1 is a perspective view showing an EFEM 100 including a buffermodule 170 according to an exemplary embodiment of the presentinvention.

Referring to FIG. 1, the EFEM 100 may selectively include a transferchamber 110, a load port module 130, a wafer transfer robot 150 (seeFIG. 8), and a buffer module 170.

The transfer chamber 110 occupies a rear portion of the EFEM 100 andforms an internal space in which the wafer transfer robot 150 operates.The transfer chamber 110 is disposed to face process equipment, forexample, deposition equipment, etching equipment, and the like.

The load port module 130 occupies a front portion of the EFEM 100. Theload port module 130 may be disposed to face the transfer chamber 110.The load port module 130 has a support 131 on which a wafer receivingcontainer, for example, a front-opening unified pod (FOUP) C is seated.In the present exemplary embodiment, the load port module 130 includesthree supports 131 so that three FOUPs C may be seated on the load portmodule 130 at a time. In order to allow the wafer transfer robot 150 toaccess the FOUP C, a door 135 is formed in the load port module 130 tocorrespond to each support 131.

The wafer transfer robot 150 operates in the transfer chamber 110, andis configured to transfer a wafer before processing in the FOUP C to aprocess equipment side. Further, the wafer transfer robot 150 transfersa wafer after processing to a load port module 130 side and puts it intothe FOUP C.

The buffer module 170 is located above the load port module 130 and thetransfer chamber 110 and provides a space for storing the FOUP Ctherein. To this end, the buffer module 170 may have a storage housing171, a buffer port 173, and a lift unit 175. The storage housing 171,which is a box having substantially a form of a rectangularparallelepiped, may have a receiving space of the form in which a frontthereof is opened. It is also possible that not only the front of thereceiving space but also the upper, rear, and the like are furtheropened. In addition, the storage housing 171 may be the storage housing171 as a part of the configuration of the EFEM 100 as well as a storagehousing put next to a rail R while being suspended from a ceiling.Further, the storage housing 171 may be a housing of a wafer stockerthat is installed on a ground. The buffer port 173 may be configured tobe moved between an inside and an outside of the storage housing 171through the front opened space of the storage housing 171. The lift unit175 is configured to transfer the FOUP C seated on the buffer port 173to the load port module 130, or transfer the FOUP C in an oppositedirection. The FOUP C is stored in the buffer module 170 before or afterit is seated on the load port module 130, and is injected with an inertgas while being seated in the buffer port 173. The inert gas may be, forexample, nitrogen, and the wafer in the FOUP C is purged by the inertgas to prevent oxidation. In the present exemplary embodiment, fourbuffer ports 173 are provided and the number of buffer ports 173 is onemore than three supports 131 of the load port module 130. Here, thebuffer ports corresponding to the three supports 131 of the buffer port173 may be referred to as a corresponding buffer port, and the other onemay be referred to as a non-corresponding buffer port. The lift unit 175is configured to be moved between positions corresponding to both thecorresponding buffer port and the non-corresponding buffer port.

According to such a configuration, a vehicle V constituting an overheadhoist transport (OHT) system reaches a position corresponding to theEFEM 100 while moving along a rail R. The vehicle V may unload the FOUPC that is being transferred to the buffer port 173 of the buffer module170. To this end, the buffer port 173 may be moved to the outside of thestorage housing 171 and wait to take over the FOUP C. The buffer port173 taking over the FOUP C may move to the inside of the storage housing171. Further, the FOUP C is injected with the inert gas while beingstored in the buffer module 170 and the wafer in the FOUP C may bepurged.

The lift unit 175 may put down the FOUP C subjected to the purge on theload port module 130. With respect to the FOUP C put down on the loadport module 130, the wafer transfer robot 150 in the transfer chamber110 may transfer the purged wafer to the process equipment side. When awork on the wafer is completed on the process equipment side, the wafertransfer robot 150 puts the wafer into the FOUP C seated on the loadport module 130. The FOUP C receiving the processed wafer is transferredto the buffer port 173 by the lift unit 175. When the FOUP C receivingthe processed wafer needs to wait for a long time, the buffer module 170additionally injects the inert gas into the FOUP C. Thereafter, thevehicle V grasps the FOUP C and moves along the rail R toward the otherprocess equipment.

In such a process, the injection of the inert gas to the FOUP C andhence the purge of the wafer is performed at a step before or after theFOUP C is seated on the load port module 130, not a step in which theFOUP C is seated on the load port module 130. In other words, theinjection of the inert gas to the FOUP C is performed in the buffermodule 170 which is separate from the load port module 130. Even if theinjection of the inert gas to the FOUP is performed in the load portmodule 130, this is at a level that complements a function of the buffermodule 170, so that the waiting time of the FOUP C in the load portmodule 130 does not become long.

The buffer module 170 described above will be described in more detailwith reference to FIG. 2. For convenience of explanation, the buffermodule 170 is also referred to as 200 by reference numeral.

FIG. 2 is an assembled perspective view showing a configuration relatedto a buffer port 220 of a buffer module 200 of FIG. 1, FIG. 3 is anexploded perspective view of a configuration related to the buffer port220 of FIG. 2, and FIG. 4 is a block diagram describing a gas supplyline 260 installed in the buffer module 200 of FIG. 3.

Referring to the present drawings, the buffer module 200 includes amount 210, a buffer port 220, a shelf installation 230, an informationmanagement unit 240, a chucking unit 250, and a gas supply line 260.

The mount 210 is a member installed in a frame 171 a of the storagehousing 171 (see FIG. 1). The mount 210 may have a generally rectangularplate shape. A guide 211 extending along an outward direction F and aninward direction R may be installed on an upper surface of the mount210. The guide 211 supports the buffer port 220 moving in the outwarddirection F and the inward direction R and guides a movement of thebuffer port 220. In addition, a buffer port driving unit 215 may beinstalled parallel to the guide 211. The buffer port driving unit 215which, is an actuator for driving the buffer port 220 in the outwarddirection F and the inward direction R, may be, for example, a rodlesscylinder.

The buffer port 220 supports the FOUP C (see FIG. 1) and is aconfiguration that assists filling of the inert gas with FOUP C. Thebuffer port 220 may structurally include a shelf 221, a cover 223, and abase 225. The shelf 221 is exposed to an upper portion to support theFOUP C in contact with the FOUP C. The cover 223 is disposed to surrounda periphery of the shelf 221. The base 225 may be disposed substantiallyparallel to the shelf 221 below the shelf 221. The chucking unit 250 andthe like may be disposed in a space defined by the shelf 221, the cover223, and the base 225. The base 225 is slidably coupled to the guide 211and is connected to the buffer port driving unit 215 to be slidablymoved in the outward direction F and the inward direction R.

The shelf installation 230 may include various structures installed onthe shelf 221 and interacting with the FOUP C. The shelf installation230 may have a reference pin 231, a supply nozzle 233, an exhaust nozzle234, and a seating detection sensor 235 in detail. The reference pin 231is a configuration inserted into a reference groove (not shown) of theFOUP C to guide the FOUP C to be correctly positioned on the shelf 221.The supply nozzle 233 is a configuration connected to an injection portof the FOUP C pressed on the shelf 221 to inject the inert gas into theFOUP C. The number of the supply nozzles 233 is plural, and for example,three supply nozzles may be located in each corner region of the shelf.Further, similarly to the supply nozzle 233, the exhaust nozzle 234 mayalso be constituted by one nozzle. The exhaust nozzle 234 is a passagethrough which the inert gas supplied into the FOUP C is discharged tothe outside of the FOUP C through an exhaust gas line (not shown). Theseating detection sensor 235 is installed on the shelf 221 to detect theseating of the FOUP C, Further, since a plurality of seating detectionsensors 235 are configured, another detection result according to ashape of the FOUP C is obtained. Accordingly, the shape of the FOUP Cmay be determined through the detection result of the seating detectionsensor 235.

The information management unit 240 is installed in the shelf 221 and isconfigured to communicate with an information storage unit (not shown)of the FOUP C. Specifically, the information storage unit of the FOUP Cstores wafer information about the wafer received in the FOUP C. Theinformation management unit 240 may communicate with the informationstorage unit to acquire the wafer information and further transmit newinformation to the information storage unit to add to the waferinformation. Here, the new information may be purge information which isinformation on the purge of the wafer. The purge information may includeinformation on a purge time, a flow rate of gas injected for purge, andthe like. To this end, the information management unit 240 may be aradio frequency identification (RFID) reader/writer, and the informationstorage unit may be an RFID tag.

The chucking unit 250 is a configuration put at the center of the shelf221 to chuck the FOUP C placed on the shelf 221.

The gas supply line 260 is a configuration that communicates with a gassupply facility of a semiconductor production factory so as to fill theinert gas in the FOUP C. The gas supply line 260 may specificallyinclude a shelf-dedicated regulator 261, a proportional pressure controlvalve unit 263, a flow rate sensor 265, and a filter 267.

The shelf-dedicated regulator 261 is a configuration that communicateswith the gas supply facility of the factory through a pipe, anddepressurizes the inert gas supplied from the gas supply facility tomaintain it at a constant pressure. Since the shelf-dedicated regulator261 is provided for each shelf 221, it is exclusively used for only thegas supply line 260 installed in the shelf 221. The inert gas suppliedto the proportional pressure control valve unit 263 located on adownstream side of the gas supply line 260 by the shelf-dedicatedregulator 261 always maintains a set pressure and is free from a huntingphenomenon.

The proportional pressure control valve unit 263 is a configuration thatcontrols the flow rate of the inert gas to supply the inert gas havingthe constant pressure input through the shelf-dedicated regulator 261 tothe FOUP C to a required level. The proportional pressure control valveunit 263 is a configuration that adjusts an area of the portion throughwhich the inert gas passes in the valve to adjust the pressure of theinert gas and further the flow rate thereof. Thereby, the flow rate ofthe inert gas may be adjusted analogously, and the degree of precisionof the flow rate adjustment may be significantly increased. According tothe inventor's experiment, an error of the flow rate adjustment is only0.4%. Three proportional pressure control valve units 263 may beprovided corresponding to the three supply nozzles 233. The inert gaspassing through the shelf-dedicated regulator 261 branches into threelines and is input to each proportional pressure control valve unit 263.

The flow rate sensor 265 is a configuration disposed downstream of theproportional pressure control valve unit 263 to indicate the flow rateregulated through the proportional pressure control valve unit 263.Since the flow rate sensor 265 is exposed to the outside through anopening of the cover 223, an operator may visually detect the flow rate.

The filter 267 is a configuration disposed between the flow rate sensor265 and the supply nozzle 233 to remove foreign materials from the inertgas.

In the above description, the shelf-dedicated regulator 261, theproportional pressure control valve unit 263, and the like constitutingthe gas supply line 260 are illustrated as being mounted on the base225, but in the absence of the base 225, the shelf-dedicated regulator261, the proportional pressure control valve unit 263, and the like mayalso be mounted on a bottom surface of the shelf 221. Further, aconfiguration in which the shelf 221, the shelf installation 230, andthe gas supply line 260 are combined may be referred to as a waferpurging-type shelf assembly.

The proportional pressure control valve unit 263 will be described withreference to FIGS. 5 and 6. For convenience of explanation, theproportional pressure control valve unit 263 is also referred to as 300by reference numeral.

FIG. 5 is a conceptual view showing a configuration of a proportionalpressure control valve unit 300 of FIG. 4.

Referring to FIG. 5, the proportional pressure control valve unit 300may include a valve housing 310, a piezo valve seat 330, a return spring350, and a pressure sensor 370.

The valve housing 310 may be a hollow body having an internal space. Aplurality of ports may be opened in the valve housing 310. As theplurality of ports, an input port 311, an output port 313, and a reliefport 315 are illustrated in the present exemplary embodiment. The inertgas having a constant pressure flows into the input port 311 through theshelf-dedicated regulator 261 (see FIG. 4). The inert gas whose flowrate is adjusted by the piezo valve seat 330 is output through theoutput port 313 to flow toward the flow rate sensor 265 (see FIG. 4).The relief port 315 is used to exhaust a part of the inert gas in theinternal space.

The piezo valve seat 330 is disposed in the internal space and opens andcloses the input port 311 and the relief port 315. The piezo valve seat330 includes a piezo material and is deformed by an applied voltage tovary the degree of opening and closing of the input port 311 and thelike. Specifically, depending on how far the piezo valve seat 330closing the input port 311 is bent away from the input port 311, thepressure and the flow rate of the inert gas, which pass through theinput port 311 and are output to the output port 313, are varied. Thisis because an area that the inert gas passes through a space between theinput port 311 and the piezo valve seat 330 is varied depending on thedegree of bending of the piezo valve seat 330.

The return spring 350 is installed to connect the piezo valve seat 330and the valve housing 310 to each other. Thereby, the return spring 350serves to return the piezo valve seat 330 which is bent away from theinput port 311 or the like while being bent according to the voltageapplication toward the input port 311 or the like when the voltageapplication is reduced/released.

The pressure sensor 370 is a configuration that measures a pressure ofthe inert gas whose flow rate is adjusted through the output port 313 ofthe valve housing 310 and is output. Since the pressure sensor 370 isembedded in the proportional pressure control valve unit 300 asdescribed above, it is not necessary to provide a separate pressuresensor on the outside. In addition, since the pressure sensor 370measures the pressure of the inert gas input to the FOUP C through thesupply nozzle 233 in the gas supply line 260 (see FIG. 4), the pressuresensor 370 may provide pressure information that allows the detection asto whether the inert gas is properly input to the FOUP C or leakswithout being input to the FOUP C. Specifically, when the inert gas isnormally injected into the FOUP C, the pressure is higher than when theinert gas leaks. This is because the pressure of the inert gas isincreased by a reaction force of the filter installed at the injectionport of the FOUP C. By using the above-mentioned point, it is necessaryto provide a separate pressure sensor or a flow rate sensor to check thegas leakage between the supply nozzle 233 and the FOUP C on the gasexhaust line through which the gas exhausted from the FOUP C flows.

A change in the pressure of the shelf-dedicated regulator 261 in such aproportional pressure control valve unit 300 and a change in an outputflow rate of the inert gas according to the change in the voltageapplied to the piezo valve seat 330 will be described with reference toFIG. 6.

FIG. 6 is a graph showing an experiment result on the proportionalpressure control valve unit 300 of FIG. 5 and FIG. 7 is a graph showingan ideal change of an inert gas flow rate supplied to a FOUP C by theproportional pressure control valve unit 300 of FIG. 5.

Referring to FIG. 6, the input pressure of the inert gas adjusted by theshelf-dedicated regulator 261 (see FIG. 4) is adjusted to 2 Bar, 3 Bar,and 4 Bar, respectively. Despite such a change in pressure, when thevoltage applied to the piezo valve seat 330 is 0.80 V or less, the flowrate through the proportional pressure control valve unit 300 shows thesame value. For example, at 0.80 V, the flow rate is 13.0 l/minregardless of the input pressure of the inert gas, and the flow rate at0.30 V is 7.9 l/min.

When the pressure of the inert gas adjusted by the shelf-dedicatedregulator 261 is 2 Bar, if the applied voltage is 0.94 V or more, theflow rate shows the same value of 13.6 l/min. In other words, even whenthe applied voltage exceeds 0.94 V and reaches 3.00 V, the flow ratedoes not exceed 13.6 l/min.

In contrast, when the pressure of the inert gas adjusted by theshelf-dedicated regulator 261 is 3 Bar, if the applied voltage is 1.76 Vor more, the flow rate shows the same value of 19.7 l/min.

When the input pressure of the inert gas adjusted by the shelf-dedicatedregulator 261 is 4 Bar, the flow rate continuously increases to 26.3l/min while the applied voltage is increased to 3.00 V. As the flow rateincreases, rapid filling of the inert gas to the FOUP C becomespossible. Accordingly, when the FOUP C is just put on the shelf 221, therapid filling to the FOUP C may be performed.

Specifically, referring to FIG. 7, the FOUP C put on the shelf 221 neednot always be supplied with the same flow rate of the inert gas. In aninitial stage, the supply flow rate should be large, but after the inertgas is sufficiently filled in the FOUP C after a certain time passes andan inert gas atmosphere is formed, the supply flow rate does not need tobe large. Thereby, a proper supply amount of the inert gas sharplydecreases after a certain time passes, and thereafter, it is maintainedat a minimum amount. On the other hand, if the inert gas is supplied tothe FOUP C at the same flow rate, this causes a great waste of the inertgas.

It may be seen from these results that there is a limit to increase theflow rate of the inert gas output from the proportional pressure controlvalve unit 300 only by increasing the applied voltage applied to thepiezo valve seat 330 in the proportional pressure control valve unit300. In order to solve such a limit, the input pressure of the inert gassupplied to the proportional pressure control valve unit 300 needs to beincreased. In such a process, when the pressure of the inert gassupplied to the proportional pressure control valve unit 300 is notuniform and the hunting phenomenon occurs, the proportional pressurecontrol valve unit 300 does not output a set flow rate. Therefore, it isimportant that the shelf-dedicated regulator 261 for supplying the inertgas of a predetermined pressure to the proportional pressure controlvalve unit 300 is disposed at an upstream side of the proportionalpressure control valve unit 300.

Further, the point of time at which the FOUP C is placed on each shelf221 is different. Therefore, whether a rapid filling time interval T₁, adeceleration filling time interval T₂, or a low-speed filling timeinterval T₃ differs depending on each of the shelves 221. It isimportant that the shelf-dedicated regulator 261 is disposed for eachshelf 221 so that different filling types for each shelf 221 may bestably and reliably achieved.

Next, a control method for the above-mentioned EFEM 100 will bedescribed with reference to FIG. 8.

FIG. 8 is a control block diagram for the EFEM 100 of FIG. 1.

Referring to FIG. 8 (and the preceding drawings), the EFEM 100 mayfurther have an EFEM control unit 190. The EFEM control unit 190 is aconfiguration that controls most of the configuration of the EFEM 100except for the buffer module 170. For example, the EFEM control unit 190may control the wafer transfer robot 150.

Unlike the above, the buffer module 170 may be controlled by a buffercontrol unit 270. The buffer control unit 270 may receive a detectionresult or a control command from the seating detection sensor 235 and auser input unit 271. Here, the user input unit 271 may be an input meanssuch as a keyboard, a touch pad, or the like.

The buffer control unit 270 may control the lift unit 175, the bufferport driving unit 215, the information management unit 240, the chuckingunit 250, and the proportional pressure control valve unit 263 based onsuch a detection result.

For example, the buffer control unit 270 may determine the shape of theFOUP C based on the detection result of the seating detection sensor235. Depending on the determined shape type of the FOUP C, the buffercontrol unit 270 may selectively intermit the supply of the inert gas toeach of the plurality of supply nozzles 233. This may be achieved by thebuffer control unit 270 closing or opening the proportional pressurecontrol valve unit 263. Accordingly, the inert gas may be supplied inthe shape corresponding to the structure of the FOUP C even in a fieldin which different shapes of FOUPs C are used.

In addition, the buffer control unit 270 may control the gas supply line260 for the FOUP C to purge the wafer by filling the inert gas and maythen allow the purge information about the purge operation to be writtento the information storage unit of the FOUP C Specifically, the buffercontrol unit 270 controls the information management unit 240 to causethe purge information to be transmitted to the information storage unit.Thereby, the wafer information may be updated to reflect the purgeinformation. Then, a central control system of the semiconductor factorymay read the information storage unit and may detect a current state ofthe FOUP C.

In addition, the buffer control unit 270 may adjust the voltage to beapplied to the piezo valve seat 330 in the proportional pressure controlvalve unit 263 based on the flow rate of the inert gas to be filled intothe FOUP C. By such a voltage adjustment, the flow rate of the inert gasfilled in the FOUP C via the proportional pressure control valve unit263 may be adjusted.

The wafer purging-type shelf assembly and the buffer module having thesame as described above are not limited to the configuration and theoperation method of the above-mentioned exemplary embodiments. Theabove-mentioned exemplary embodiments may be configured so that variousmodifications may be made by selective combinations of all or some ofthe respective exemplary embodiments.

According to the wafer purging type shelf assembly and the buffer moduleaccording to the exemplary embodiments of the present invention havingthe configurations as described above, the gas supply line maycommunicate with the wafer receiving container through the supply nozzlein a state in which the wafer receiving container is put on the shelf,and may precisely control the supply flow rate of the inert gas by theproportional pressure control valve unit through the area control. Sincethe proportional pressure control valve unit is less expensive than theconventional mass flow controller and requires only a small installationspace, the proportional pressure control valve unit is suitable for widefield applications. Further, the waste of the inert gas may beeliminated by controlling the supply flow rate of the inert gas.

In addition, since the shelf-dedicated regulator exclusively used forthe corresponding proportional pressure control valve unit to input theinert gas into the corresponding proportional pressure control valveunit at a uniform pressure is provided to the upstream side of theproportional pressure control valve unit, the flow rate of the inert gasthrough the proportional pressure control valve unit may be greatlyincreased by increasing the pressure of the inert gas input to theproportional pressure control valve unit. Thereby, the filled amount ofthe inert gas to the wafer receiving container may be rapidly improvedat a point of time at which the wafer receiving container is put on theshelf.

What is claimed is:
 1. A wafer purging-type shelf assembly comprising: astorage housing including a receiving space; a shelf formed to support awafer receiving container in the receiving space; a supply nozzleconfigured to be connected to an injection port of the wafer receivingcontainer; and a gas supply line configured to supply an inert gasdischarged from a factory gas facility to the wafer receiving containerthrough the supply nozzle, wherein the gas supply line includes aproportional pressure control valve unit, a shelf-dedicated regulator, aflow rate sensor and a filter wherein the proportional pressure controlvalve unit adjusts a supply flow rate of the inert gas to the waferreceiving container by an area control method; wherein the proportionalpressure control valve unit includes: a valve housing including an inputport, a relief port and an output port; and a piezo valve seat, arestoring spring being installed inside the valve housing and a pressuresensor being outside the valve housing and the piezo valve seatadjusting a flow area of the inert gas through the input port accordingto an input voltage to control a flow rate of the inert gas outputthrough the output port.
 2. The wafer purging-type shelf assembly ofclaim 1, wherein the restoring spring pressurizes the piezo valve seatin a direction of closing the input port.
 3. The wafer purging-typeshelf assembly of claim 1, wherein the pressure sensor measures apressure of the inert gas output through the output port.
 4. The waferpurging-type shelf assembly of claim 1, wherein the shelf-dedicatedregulator is installed at an upstream side of the proportional pressurecontrol valve unit and is configured to supply the inert gas only to theproportional pressure control valve unit at a uniform pressure.
 5. Thewafer purging-type shelf assembly of claim 4, wherein theshelf-dedicated regulator is disposed below the shelf.
 6. The waferpurging-type shelf assembly of claim 1, wherein the flow rate sensor isdisposed between the proportional pressure control valve unit and thesupply nozzle to output a flow rate of the inert gas passing through theproportional pressure control valve unit.
 7. The wafer purging-typeshelf assembly of claim 1, wherein the filter is installed at anupstream side of the supply nozzle to filter foreign materials of theinert gas.